Re: another OATS question
That's what I thought. The same approach must be used whether measuring site attenuation or measuring RE from the test sample, right? I don't understand how it could work otherwise. From: brent.dew...@us.datex-ohmeda.com Reply-To: brent.dew...@us.datex-ohmeda.com Date: Mon, 23 Jun 2003 12:58:55 -0600 To: Ken Javor ken.ja...@emccompliance.com Cc: emc-p...@majordomo.ieee.org Subject: Re: another OATS question Hi Ken, Only the maximum reading over the scan height is used. The received signal is nominally the vector sum of the line of sight path and the reflected or image path from the ground plane. In horizontal polarization there is also 180 degree phase shift due to conservation of charge physics with the ground plane. Best regards, Brent DeWitt --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: another OATS question
Tim Pierce wrote I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area ... Tim, If this were a reflector antenna, holes in the reflector would be kept to 0.1 wavelength at the highest frequency. This results -- if reflections are only from the defined surface -- in a loss to feed-through of 1 dB. Keeping surface irregularities to less than one eight wavelength insures the phase of reflected signals is accurate enough to keep the resultant within about 1 dB of the maximum possible, too. If we take 1 dB for each of these effects, we might use up half of our error budget for an FCC site. However, when considered as a reflector, it appears the care we lavish on much of our ground plane is unneeded. Try ray-tracing the site to see what I mean; where horizontal polarization is used, areas near the EUT and the receiving antenna don't generate any reflections between EUT and antenna. They would affect propagation of vertically polarized signals at the lower frequencies. This suggests that we need to take more care near the middle two-thirds or so of our sites than near the EUT and antenna. I don't recall seeing any papers on thinning a ground plane away from areas supporting reflections, though Speeding up the process? Well, when broadband antennas are used you can semi-automate the procedure. OATS being subject to ambients, and max hold being unintelligent about what it holds ON, an operator is needed to be sure erroneous data points aren't collected. I suppose a modulated signal could be used, and results taken through a narrow band detector, reducing the probability of ambients being taken for data, but most of us prefer to stay as close to agency-accepted methods as possible. The signal generator is another matter, as many are controllable remotely -- or you can use a tracking generator or network analyzer. If you have enough RF, or use a post-generator amplifier, you can locate ALL your equipment in the control room. Of course we are limited to Part 15 levels for all this. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: another OATS question
Hi Ken, Only the maximum reading over the scan height is used. The received signal is nominally the vector sum of the line of sight path and the reflected or image path from the ground plane. In horizontal polarization there is also 180 degree phase shift due to conservation of charge physics with the ground plane. Best regards, Brent DeWitt This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: another OATS question
I read in !emc-pstc that drcuthb...@micron.com wrote (in E6F64B42266D6 54b80a0f7f4b98212a50f3...@ntxboimbx03.micron.com) about 'another OATS question' on Mon, 23 Jun 2003: This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. Yes, well, for some people that's the Holy Grail. For them, the purpose of testing is to fail products, not to pass them. While their influence has declined in recent years, there are still traces of their earlier achievements. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Okay,that clears it up for me. I need to take a look at the NSA method. There has been much talk in articles and on the web about the flaws in the NSA method. Dave Cuthbert Micron Technology From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Monday, June 23, 2003 12:09 PM To: drcuthbert; ieee pstc list Subject: RE: another OATS question Dave Cuthbert (drcuthb...@micron.com) wrote: If I understand the OATS cal procedure, the RX antenna height is moved from 1 meter to 4 meters and readings are taken. Now this is the strange part: The readings are averaged. Is this right? Now think about it- when a DUT is tested, the RX antenna is moved until maximum signal is achieved- not the average signal as the RX antenna height is swept. This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. My understanding is that one *doesn't* average readings taken while scanning heights, but that receive antenna height is varied at each frequency to obtain maximum signal strength over the heights scanned. That reading is used. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Dave Cuthbert (drcuthb...@micron.com) wrote: If I understand the OATS cal procedure, the RX antenna height is moved from 1 meter to 4 meters and readings are taken. Now this is the strange part: The readings are averaged. Is this right? Now think about it- when a DUT is tested, the RX antenna is moved until maximum signal is achieved- not the average signal as the RX antenna height is swept. This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. My understanding is that one *doesn't* average readings taken while scanning heights, but that receive antenna height is varied at each frequency to obtain maximum signal strength over the heights scanned. That reading is used. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: another OATS question
I have to confess to complete ignorance here. I had no idea that the measurements made during a height search were averaged. I though the NSA curve was based on a specular reflection from a perfect ground plane, in which case only the peak measurement during a height scan could correlate to the NSA curve. Could someone on the list explain how correlation is achieved through averaging? From: drcuthb...@micron.com Reply-To: drcuthb...@micron.com Date: Mon, 23 Jun 2003 10:40:29 -0600 To: luke.turnb...@trw.com, emcp...@aol.com, emc-p...@majordomo.ieee.org Subject: RE: another OATS question Yes that will work too. I like the SNA or VNA because they calibrate out the cable loss. As I understand it, one connects the RX and TX antenna cables together and then performs a two-port cal. Then connect the cables to their respective antennas and read S21 or S12 (should be the same either way). Then only the AF needs to be factored in. If I understand the OATS cal procedure, the RX antenna height is moved from 1 meter to 4 meters and readings are taken. Now this is the strange part: The readings are averaged. Is this right? Now think about it- when a DUT is tested, the RX antenna is moved until maximum signal is achieved- not the average signal as the RX antenna height is swept. This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. If the cal consisted on taking only the maximum signal, then the correct height could be determined by simulations and the antenna could be swept close to this height. Much less data to take. These antenna heights will of course be different for horizontal and vertical polarization. Dave Cuthbert Micron Technology -Original Message- From: Luke Turnbull [mailto:luke.turnb...@trw.com] Sent: Monday, June 23, 2003 2:24 AM To: emcp...@aol.com; emc-p...@majordomo.ieee.org; drcuthbert Subject: RE: another OATS question Or a Spectrum analyser with tracking generator. drcuthb...@micron.com 06/20/03 06:58pm Renting a VNA or SNA would really speed things up. Dave -Original Message- From: emcp...@aol.com [mailto:emcp...@aol.com] Sent: Friday, June 20, 2003 10:02 AM To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc
RE: another OATS question
I think that NSA is done with the maximum over a height scan as well, hence the Spec Ana is good because you can put it on max hold. Luke Turnbull drcuthb...@micron.com 06/23/03 05:40pm Yes that will work too. I like the SNA or VNA because they calibrate out the cable loss. As I understand it, one connects the RX and TX antenna cables together and then performs a two-port cal. Then connect the cables to their respective antennas and read S21 or S12 (should be the same either way). Then only the AF needs to be factored in. If I understand the OATS cal procedure, the RX antenna height is moved from 1 meter to 4 meters and readings are taken. Now this is the strange part: The readings are averaged. Is this right? Now think about it- when a DUT is tested, the RX antenna is moved until maximum signal is achieved- not the average signal as the RX antenna height is swept. This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. If the cal consisted on taking only the maximum signal, then the correct height could be determined by simulations and the antenna could be swept close to this height. Much less data to take. These antenna heights will of course be different for horizontal and vertical polarization. Dave Cuthbert Micron Technology From: Luke Turnbull [mailto:luke.turnb...@trw.com] Sent: Monday, June 23, 2003 2:24 AM To: emcp...@aol.com; emc-p...@majordomo.ieee.org; drcuthbert Subject: RE: another OATS question Or a Spectrum analyser with tracking generator. drcuthb...@micron.com 06/20/03 06:58pm Renting a VNA or SNA would really speed things up. Dave From: emcp...@aol.com [mailto:emcp...@aol.com] Sent: Friday, June 20, 2003 10:02 AM To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Yes that will work too. I like the SNA or VNA because they calibrate out the cable loss. As I understand it, one connects the RX and TX antenna cables together and then performs a two-port cal. Then connect the cables to their respective antennas and read S21 or S12 (should be the same either way). Then only the AF needs to be factored in. If I understand the OATS cal procedure, the RX antenna height is moved from 1 meter to 4 meters and readings are taken. Now this is the strange part: The readings are averaged. Is this right? Now think about it- when a DUT is tested, the RX antenna is moved until maximum signal is achieved- not the average signal as the RX antenna height is swept. This method makes a DUT look hotter than it really is and makes the site uncertainty appear larger. If the cal consisted on taking only the maximum signal, then the correct height could be determined by simulations and the antenna could be swept close to this height. Much less data to take. These antenna heights will of course be different for horizontal and vertical polarization. Dave Cuthbert Micron Technology From: Luke Turnbull [mailto:luke.turnb...@trw.com] Sent: Monday, June 23, 2003 2:24 AM To: emcp...@aol.com; emc-p...@majordomo.ieee.org; drcuthbert Subject: RE: another OATS question Or a Spectrum analyser with tracking generator. drcuthb...@micron.com 06/20/03 06:58pm Renting a VNA or SNA would really speed things up. Dave From: emcp...@aol.com [mailto:emcp...@aol.com] Sent: Friday, June 20, 2003 10:02 AM To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Hello Tim At one of our OATS sites we have a pit under a metal hatch in the groundplane, to the rear of the EUT turntable. To do the NSA we put the signal generator down there and connect it back to the control room via a fibre optic/GPIB link. I wrote some software which steps the sig gen through the necessary frequency steps, and drives the RX antenna up and down the 4m mast, taking readings from the receiver every few centimetres. Once the direct connection readings have been taken, and the broadband antennas have been connected, I can set it running and leave it. It takes about 2 hours to collect and analyse the data for the NSA. Of course, such a system can only be implemented once the location of the site is decided. Yes, doing it manually, especially with dipoles, takes a large slice out of your life! Regards Steve Seller DISCLAIMER NOTICE http://www.yorkemc.co.uk/Disclaimer York EMC Services, Market Square, The University of York, Heslington, York, YO10 5DD. VAT Reg No: GB 647 2055 41 Company Reg No: 3075474 York EMC Services Ltd is a Company limited by guarantee and not having share capital. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Or a Spectrum analyser with tracking generator. drcuthb...@micron.com 06/20/03 06:58pm Renting a VNA or SNA would really speed things up. Dave From: emcp...@aol.com [mailto:emcp...@aol.com] Sent: Friday, June 20, 2003 10:02 AM To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: another OATS question
Renting a VNA or SNA would really speed things up. Dave From: emcp...@aol.com [mailto:emcp...@aol.com] Sent: Friday, June 20, 2003 10:02 AM To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce
Re: another OATS question
Electrometrics makes a dipole set that is self-tuning. From: emcp...@aol.com Reply-To: emcp...@aol.com List-Post: emc-pstc@listserv.ieee.org List-Post: emc-pstc@listserv.ieee.org List-Post: emc-pstc@listserv.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Fri, 20 Jun 2003 12:02:19 EDT To: emc-p...@majordomo.ieee.org Subject: another OATS question Hello everyone, I have worked with sites that used the hardware cloth (screen) over concrete in the past. When the tears would happen, they would patch that area with screen to cover the hole and maintain continuity. Can this patching create a problem with site attenuation, if there are too many patches? I was planning to build the site with concrete underneath the screen. Also, do you know of a way to do the site attenuation faster? In the past, I have used tunable dipoles (takes forever) and also broadband antennas, which is a little faster. Normally, I have done the site attenuation with the signal generator about 10 feet behind the transmitting antenna. This means that you have to go outside, change the frequency, go inside and make the measurement, then back outside again. All I have to work with is a signal generator and spectrum analyzer. Would it make a difference to have the signal generator inside the building (this means that the output cable to the antenna would be approx. 30 feet long.) I guess as long as this long cable for the transmit antenna is counted in the V direct reading, it should be ok? Making site measurements faster will help me evaluate my proposed site location. Thanks for your input. Tim Pierce
